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Tricks of the trade for the metrically challenged

In an earlier blog post I wrote about the many little differences in daily culture that can sometimes frustrate expats in German-speaking Europe. I listed 15 “Kleinigkeiten” that may or may not be minor matters – from traffic signal placement to the bare kitchen. But today we’ll discuss a different sort of pesky cultural difference, and how to cope with it.

This almost exclusively concerns US-Amerikaner (as the Germans so accurately say). We US Americans are the last of a dying breed: people who do not use the metric system. The United States of America is one of the few places left on earth where average people still measure things in feet and inches or yards and miles. Americans are also left out in the cold when it comes to measuring temperatures. Almost no one else uses degrees Fahrenheit any more. Even the British have moved on to the Celsius system, although in their muddling way road signs are still in miles and you can still order a pint of beer. Metricizing (metricising) has its limits in the UK.

Metric measure is not a problem for non-Americans moving to Austria, Germany or Switzerland. Even the Canadians went metric back in the 1970s. (It is only commercial and cultural ties to the US that keeps some vestiges of non-metric alive in Canada.) Because metrication never really caught on in the US, we Americans are handicapped when we leave our familiar shores.

So you finally learned your German numbers and you can actually understand a basic weather forecast in German, but how warm or cold is 15 degrees Celsius? How deep is 8 centimeters of snow? After a while, expats learn these things, but what if you want to convert certain measurements for yourself or friends and relatives in the US – without a calculator, computer or smartphone?

Here are seven (7) shortcut methods that allow you to do these conversions in your head. Even a non-math person like me can do it!

1. Celsius (centigrade) to Fahrenheit. Double the Celsius degrees and add 30 (not 32!). This is a surprisingly accurate shortcut that works for average daily temperatures. If it’s 10°C, double that (20) and add 30 = 50°F (actual answer: 50°F!). If it’s 25°C, you double that to 50 and add 30, which gives you 80°F. The precise answer is 77°F. This shortcut also works for minus temperatures: -5°C x 2 = -10 + 30 = 20°F (precise answer: 23°F). – Trivia: Which temperature is identical in Celsius and Fahrenheit? In other words, at which identical number on both temperature scales would you feel exactly as hot or cold? (See answer below.)

2. Kilometers to miles. Use the six-tenths-rule (the 0.6-rule) to get a good ballpark figure for distances or speed. If something is 50 km away, it’s 30 miles away (0.6 x 50 = 30, or multiply by 6 and drop a zero). The precise answer is 31.07 miles (0.621 x 50; one kilometer = 0.621 mi), but our rough figure is pretty close. For longer distances you can get closer by adding a “fudge factor” of 3%. For instance, 500 km multiplied by 0.6 is 300 miles, but you get even closer by adding 3% (9) to get 309 miles. (Actual answer: 310.7 miles.) Even without adding 3%, you come close enough for most situations.

7. Centimeters to inches. Computer monitors and TV screens are the only things in Germany still measured in inches (Zoll), so this conversion can be useful. The easiest way is to memorize how many centimeters are in an inch (2.54 cm). So 5 cm = 2 inches, 10 cm = 4 inches, and so on. If there are 8 cm of snow on the ground, how many inches is that? 8 / 2.5 = 3.1 in. On a meter/yardstick you’ll see that 66 cm matches 26 inches. A yard (36 in) is slightly more than 91 centimeters. Most people simply memorize their height in centimeters. A person who is 5 feet, 9 inches tall (69 inches) is 175 cm (175.2 cm). A six-footer (72 in) is 183 cm (182.88 cm) or 1.83 m tall.

Gas Mileage (mpg)
One thing I’ve never found a good shortcut for: converting liters per 100 km to miles per (US) gallon, or vice versa. (Sorry, but dividing 235 by a l/100 km-figure is not something I can do in my head! 235 / (8 l / 100 km) = 29.4 mpg.) The reason for the difficulty is that miles per gallon (mpg) and liters per hundred kilometers (l/100 km) don’t really measure the same thing. The l/100 km figure indicates a rate of fuel consumption, while mpg is a measure of fuel economy (“gas mileage”). One system concentrates on how much fuel you use to cover a certain distance (gallons per mile), while the other (miles per gallon) concentrates on how far you can go per fuel unit. But even the almost universal metric system has no universal way to measure fuel consumption/economy. Some countries do actually use the metric equivalent of mpg (km/liter), but Germany isn’t one of them. To fully understand the difference, see this Wikipedia page, which also mentions which countries use which system.

There may be no shortcut, but there are online charts and calculators for mpg conversion. For starters, 26 mpg = 9 liters per 100 km (9.05 l for sticklers). The lower the mpg figure, the higher the liters per 100 km figure (6 mpg = 39.2 l per 100 km; 40 mpg = 5.88 l per 100 km). The Dutch, the Japanese and some others use kilometers per liter, closer to our miles per gallon: 26 mpg = 11.05 km/l. Here’s a good conversion table for both km/l and l/100 km.

A web search will also get you charts or calculators for pressure, power and other conversions that are just too complicated for simple shortcuts. If you know of a good conversion shortcut I haven’t mentioned, please leave a comment.

About HF

Born in New Mexico USA. Grew up in Calif., N.C., Florida. Tulane and U. of Nev. Reno. Taught German for 28 years. Lived in Berlin twice (2011, 2007-2008). Extensive travel in Austria, Germany, Switzerland, much of Europe, and Mexico. Book author and publisher - with expat interests.

3 thoughts on “Tricks of the trade for the metrically challenged”

Interesting tips you have there! Now, I know more about figuring and comparing European gas mileage to American gas mileage! I have 2 easy tips that I would like to make available to anyone and they’re relatively easy, but they’re used as a reference point.

To convert from Celsius to Fahrenheit (or vice versa), I use this easy reference that I picked up from Rick Steves. 28 C is about 82 F. I just reverse the 2 and 8 around. I only use this as a reference point. If the weather is 30 C, I know it’s going to be hot.

To convert liters to gallons, I know that 4 liters is roughly equal to 1 gallon. I know this because it is usually printed on most commercial toilets. After using the restrooms at work and seeing this all the time, it becomes imprinted in my head.

After some weeks here in the U.S. I found out all these helping methods for everyday life, too. But as you told, the mileage gas system is soooo different. We bought 2 cars and didn’t pay attention to the gas mileage, we just read the numbers on the paper and when my spouse found out how much liters his Jeep uses per 100km, we were more than SHOCKED. We wouldn’t probably have bought the car knowing the gas mileage system – so, a shortcut would have been helpful 🙂